1. Field of the Invention
This invention relates to a method and structure for electrically connecting an annular corrugated tube, and more particularly for example to a method and structure for electrically connecting a coaxial cable having an outer conductor with an annular corrugated outer surface as an annular corrugated tube when the end of the outer conductor is clamped by clamping members.
2. Description of the Related Art
Referring to FIG. 5, when a coaxial cable 100 is to be connected to an antenna or the like, a connector 50 is usually attached to its end. The coaxial cable 100 comprises an annular corrugated outer conductor 101 formed as an annular corrugated tube. Here, for the convenience of the following description, the concave portions of the outer conductor 101 will be referred to as grooves and the convex portions will be referred to as ridges. Accordingly, the outer conductor 101 has the shape of a tube wherein grooves and ridges are alternately periodically repeated in the axial direction of the tube. An inner conductor 102 having the shape of a straight pipe is disposed inside the outer conductor 101 coaxially therewith. An insulator 103 for electrically insulating the two conductors from each other is filled between the two conductors 101, 102. A corrosion prevention layer 104 for preventing corrosion of the coaxial cable 100 covers the outside of the outer conductor 101.
The connector 50 connected to the end of the coaxial cable 100 comprises a gripping flange 51, a connector proper 52, a connecting metal 53, an insulator 54, a contact 55, a support member 56 and a split clamp 57.
By the coaxial cable 100 being connected to the connector 50, the end of the outer conductor 101 is clamped by the support member 56 and the split clamp 57 and the outer conductor 101 of the coaxial cable 100 is electrically connected to the connector 50. Therefore, it is necessary that the end of the outer conductor 101 be clamped by the support member 56 and the split clamp 57. However, because the outer surface of the outer conductor 101 of the coaxial cable 100 is ridged and the pitch at which the grooves and ridges constituting the annular corrugated form are repeated is relatively long, the angle of slope of the ridges is also gentle.
Consequently, when the end of the outer conductor 101 has not undergone any preparatory treatment, the work of clamping the end of the coaxial cable 100 with the support member 56 and the split clamp 57 is not always easy.
As a result, conventionally, to facilitate this clamping, the end of the outer conductor 101 has been widened radially outward. When it has been widened radially outward, the end of the outer conductor 101 can be easily clamped between the support member 56 and the split clamp 57.
However, with this kind of conventional connection, the work of widening the end of the outer conductor 101 radially outward is time and labor consuming. Also, a specialized and costly tool is necessary for widening the end of the outer conductor 101. Furthermore, in order to widen the end of the outer conductor 101 radially outward it is necessary to cut the outer conductor 101 along a ridge using a cutting blade, and a complicated and expensive tool including members for guiding the cutting blade along the ridge is required for this.
Thus with an annular corrugated tube like the outer conductor described above it is costly and not easy to clamp the end of the tube to a connecting member such as a connector with clamping members.